Lower mold assembly for punching a sheet

ABSTRACT

A lower mold assembly for punching a sheet comprises a lower mold body having an upper surface; a V shape trench is formed at the upper side of the lower mold body; each lateral wall of the trench being formed with a recess; each recess being installed with an elastic element; a punching knife being installed above the lower mold body; the hardness of the elastic elements being slightly smaller than that of the lower mold body; wherein the elastic element serves to increase the tightness in punching operation and to avoid the punching traces in punching operation. A width of the lower mold body is adjustable based on a width of a sheet placed thereupon for punching. The elastic element has an irregular surface. The elastic element is made of a material selected from one of POM and elastic hard rubber.

FIELD OF THE INVENTION

The present invention relates to punching operations, and particularlyto a lower mold assembly for punching a sheet, wherein installation ofthe elastic elements makes no plastic pad being used in punchingoperation. The safety of the operator is assured. The thickness of thesheet is not confined so that the production time can be reduced.

BACKGROUND OF THE INVENTION

Referring to FIG. 1, the prior art punching device is illustrated. Inthe prior art, a lower mold seat 10 has a mold assembly 11 thereon. Aplastic pad 13 is placed upon the mold assembly 11. A folding portion ofthe mold assembly 11 is embedded with a folding knife 12 which can movelongitudinally. The mold assembly 11 can punch sheets S to be folded soas to have a desired folded shape. The above mentioned structure makesthe sheets S have no punching traces. Moreover, in the prior art, aplurality of plastic pads 13 must be prepared for suiting for differentkinds of sheets S.

Then the sheets S are shifted for punching at another positions and thusthe position of the plastic pad 13 is changed to avoid to generatepunching traces in the operation. However, above operation is based onthe skilled technology of the operator, while the safety and productionefficiency are very low by users.

SUMMARY OF THE INVENTION

Accordingly, the primary object of the present invention is to provide alower mold assembly for punching a sheet, wherein installation of theelastic elements makes no plastic pad being used in punching operation.The safety of the operator is assured. The thickness of the sheet is notconfined so that the production time can be reduced.

To achieve above objects, the present invention provides a lower moldassembly for punching a sheet. The assembly comprises a lower mold bodyhaving an upper surface; a V shape trench is formed at the upper side ofthe lower mold body; each lateral wall of the trench being formed with arecess; each recess being installed with an elastic element; a punchingknife being installed above the lower mold body; the hardness of theelastic elements being slightly smaller than that of the lower moldbody; wherein the elastic element serves to increase the tightness inpunching operation and to avoid the punching traces in punchingoperation. A width of the lower mold body is adjustable based on a widthof a sheet placed thereupon for punching. The elastic element has anirregular surface. The elastic element is made of a material selectedfrom one of POM and elastic hard rubber.

The various objects and advantages of the present invention will be morereadily understood from the following detailed description when read inconjunction with the appended drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the prior art punching operation ofthe present invention.

FIG. 2 is a perspective view of the lower mold body of the presentinvention.

FIG. 3 is an exploded schematic view of the lower mold body of thepresent invention.

FIG. 4 is a schematic view showing the operation of the presentinvention, where the punching operation is not performed.

FIG. 5 is a schematic view showing the operation of the presentinvention, where the punching operation is performed.

DETAILED DESCRIPTION OF THE INVENTION

In order that those skilled in the art can further understand thepresent invention, a description will be provided in the following indetails. However, these descriptions and the appended drawings are onlyused to cause those skilled in the art to understand the objects,features, and characteristics of the present invention, but not to beused to confine the scope and spirit of the present invention defined inthe appended claims.

With reference to FIGS. 2 and 3, the structure of the present inventionis illustrated. The present invention has the following elements. Alower mold body 2 has an upper surface. A V shape trench 21 is formed atthe upper side of the lower mold body 2. Each lateral wall of the trench21 is formed with a recess 20. Each recess 20 is installed with anelastic element 200. A punching knife 12 is installed above the lowermold body 2. The hardness of the elastic elements 200 is slightlysmaller than that of the lower mold body 2. The elastic element 200 maybe made of POM or high elastic rubber material. The elastic element 200serves to increase the tightness in punching operation and to avoid thepunching traces in punching operation. Moreover, the noise in punchingoperation can be reduced.

Referring to FIGS. 4 and 5, the sheet is placed upon the lower mold body2. The apex of the elastic element 200 is higher than the upper side ofthe lower mold body 2 and the surface B of the elastic element 200 is incontact with the sheet S at points P. When the sheet S is punched by thepunching knife 12, the elastic elements 200 will provide sufficientelasticity to the sheet S so that no undesired punching trace generatesin the surface of the sheets. This is because the point P providessufficient buffer effect to the sheet S so that the points P′ has nopunching trace.

Advantages of the present invention will be described herein. Theinstallation of the elastic elements makes no plastic pad being used inpunching operation. The safety of the operator is assured. The thicknessof the sheet is not confined so that the production time can be reduced.

The present invention is thus described, it will be obvious that thesame may be varied in many ways. Such variations are not to be regardedas a departure from the spirit and scope of the present invention, andall such modifications as would be obvious to one skilled in the art areintended to be included within the scope of the following claims.

What is claimed is:
 1. A lower mold assembly for punching a sheet; theassembly comprising: a lower mold body having an upper surface; a Vshape trench being formed at the upper side of the lower mold body; eachlateral wall of the trench being formed with a recess; each recess beinginstalled with an elastic element; a punching knife being installedabove the lower mold body; the hardness of the elastic elements beingslightly smaller than that of the lower mold body; wherein the elasticelement serves to increase the tightness in punching operation and toavoid the punching traces in punching operation.
 2. The lower moldassembly for punching a sheet as claimed in claim 1, wherein a width ofthe lower mold body is adjustable based on a width of a sheet placedthereupon for punching.
 3. The lower mold assembly for punching a sheetas claimed in claim 1, wherein the elastic element has an irregularsurface.
 4. The lower mold assembly for punching a sheet as claimed inclaim 1, wherein the elastic element is made of a material selected fromone of POM and elastic hard rubber.